The present invention is in the technical field of biotechnology. More particularly, the present invention is in the technical field of polymerase chain reaction (PCR) devices. More particularly, the present invention is in the technical field of portable PCR devices.
Since its invention, the polymerase chain reaction (U.S. Pat. No. 4,683,202) has become a powerful force in biotechnology. It is a method to exponentially amplify essentially exact copes of a DNA segment. DNA is a double stranded molecule and when heated at temperatures such as 95° C., will dissociate into two separate strands. Using small synthetic DNA fragments called primers that can complementary base pair to the dissociated DNA strands at temperatures such as 45-65° C. the primers anneal to the template DNA. Finally, elongation takes place at around 72° C. using an enzyme called a DNA polymerase to extend off of one end of the primer by adding nucleotides (dNTP's) making a new copy strand of DNA. Both of the two DNA strands are used with the annealed primers to make two new copy strands of DNA and these are called elongation events. By repeating the cycle of dissociating, annealing and elongating the reaction again, there is a doubling of new DNA strands produced. Repeat the cycle over 30 times and theoretically there are billions of exact DNA copies in the reaction vessel. These heating and cooling cycles along with the template DNA, primers, dNTP's and DNA polymerase are what constitute the PCR method. PCR is usually performed in automated devices that thermocycle the temperatures needed for the production of amplification products after all of the template DNA, primers, dNTP's and enzyme have been added to a sample vessel.
Conventional PCR devices, such as Peltier thermoelectric devices like the AB 7900 (U.S. Pat. No. 7,133,726 B1), convection heat exchangers like the Roche LightCycler (Wittwer, C. T., et al., Anal. Biochem. 186: p 328-331 (1990) and U.S. Pat. No. 5,455,175) and the like, are typically power hungry and/or difficult to transport. All these PCR devices must thermal cycle in order to heat and cool the samples vessels they hold. The 7900 does this by constructing its sample holder out of a big block of metal and pumping heat energy into and out of the system through thermal conduction. Electrical energy is required both to add heat energy to the sample block and to remove heat energy from the block. This requires a lot of electrical energy due to the large mass of the sample block. The LightCycler avoids the large sample block by using thin capillary tubes with relatively small masses and cycles the temperature by convection with heated air. Like the 7900, the heating element in the LightCycler uses a lot of electrical energy.
Most of these devices are designed to be setup in a laboratory environment and not moved from location to location because they are large and heavy. Moving such devices typically requires a strong person, or a sturdy wheeled vehicle such as a reinforced wagon or handcart. Further, it is common that these devices run off standard 120V outlet for power. Further, the devices cannot readily be moved from room to room once inside a laboratory.